A standard magnetic separator as described in German patent document 2,601,417 of J. Peace (claiming a British priority date of Sep. 5, 1975) and U.S. Pat. No. 4,055,489 of W. Soley comprises an overhead pickup belt that runs underneath a powerful magnet above a conveyor along which moves bulk material including magnetically attractable elements. Thus the magnetically attractable elements are pulled magnetically up off the conveyor belt to adhere to the pickup belt and are conveyed thereby normally transversely of the conveyor to a location offset from the conveyor where the pickup belt extends past its magnets, so that the elements are no longer held magnetically and drop off. This pickup belt is normally provided with transversely extending nonmagnetic cleats to aid moving the picked-up elements.
Such a belt is subjected to substantial wear. The elements it picks up frequently strike it with considerable force and even sometimes scrape along it. Furthermore the belt is advanced at a good speed and must bend at each end around the rollers it is spanned over.
Since it is standard to use such a magnetic separator underground in a mining operation to separate iron ores, it is essential to minimize service problems with it, as servicing such a bulky piece of equipment in a mine is extraordinarily difficult. Not only must wear and damage to the belt be minimized, but replacing the belt must also be a relatively simple project
In systems such as described in U.S. Pat. No. 2,753,980 of L. Ballard, U.S. Pat. No. 2,875,887 of T. Hinchcliffe, U.S. Pat. No. 3,147,850 of R. Ronceray, and U.S. Pat. No. 4,697,693 of G. Rajala as well as in German patent document 3,533,933 of A. Jager the belt is annularly continuous and the conveying cleats are bolted to it in various manners. With such an arrangement when the belt is worn out, it can be cut off fairly easily, but complex equipment must be employed to fit a new endless belt over the rollers. Such belt replacement can take many hours of costly down time.
In German patent documents 1,531,962 of R. Gebhardt and 2,825,207 of E. Francois (claiming U.S. priority of application 814,357 filed Jul. 11, 1977) the belts are not continuous and complex hinge joints are provided to join them so that installing a new belt is fairly simple. Nevertheless, these joints subject the rollers to considerable wear and generate a great deal of noise. The wear is an obvious problem and the extra noise can mask other noises, such as a bad bearing scrape, to create further service problems. In U.S. Pat. No. 2,930,478 of D. Ruffino the ends of the belt are oppositely cut away and bolted together, but the joint is fairly weak since the reinforcement of the belt terminates to each side of it, and the bolt heads project uselessly from the belt.